Piston-cooling system



Nov. 30 1926.

. J. T. RAUEN PISTON COOLING SYSTEM Filed June 9. 1923 Patented Nov. 30, 1926.

UNITED STATES PATENT ()FFICE.

JOHN T. RAUEN, OF DAYTON, OHIO.

PISTON-COOLING SYSTEM.

Application filed June 9,

This invention relates in general to a pis ton cooling system and more particularly to anovel method of cooling the interior of the piston of an internal combustion engins.

The problem of providing adequate cooling means for cooling the interior of the piston of internal combustion engines is a very important one, especially when the engine is of the high speed or high compression type. I am aware that others have proposed to effect this cooling by forcing a stream of oil or air against the interior of the head of such a piston by utilizing some mechanism for positively forcing or spray-- ing such a fluid against the inner side of the piston head and along its inner Walls. Such a device, however, necessitates the use of various mechanisms such as pumps or the like forcing the fluid into the interior of the piston, thus adding weight to the engine and adding further complications to its operation.

It is the purpose of my invention to provide a means for cooling the piston without any such complications by merely adding to a piston of usual form a simply constructed device which will insure a circulation of the air in the crank-case through the interior of the piston by the motion of the piston itself.

Other objects of my invention will appear in the accompanying specification and claims and will be disclosed in the accompanying drawings in which:

Fig. 1 is a central vertical section of a piston embodying my improvement.

Fig. 2 is a transverse section on the line AA of Fig. 1.

Referring with greater particularity to the drawings, it will be seen that my device is comprised as follows:

Piston 1, having the usual head 2 and piston rings 3 is shown as just completing its downward stroke in the cylinder 4. The interior of the piston along its side walls and in its head portion is provided with a plurality of reinforcing and cooling ribs 5.

My improvement consists in mounting in the piston a substantially cylindrical insert 6 having its upper end 7 terminating near the head of the piston and having its lower end terminating in a bell-shaped portion 8 slightly below the skirt 9 of the piston, the

outer diameter of the bell-shaped portion being substantially equal to or slightly 1923. Serial No. $441,510.

greater than the outer diameter of the piston skirt. The insert 6 is fixedly secured to the piston by a plurality of suitably disposed screws 10.

It will be seen that by the provision of this insert I have provided two concentric, annular passages A and B. As the piston moves downward, the air in the crank-case will rush into the bell mouth of the insert 6 and upwardly through the channel B and impinge against the head of the piston. Due to the position of the bell mouth relative to the skirt of the piston there will not be the same tendency of air to rush upwardly through channel A, but there will rather be created here an area of low compression or rarefaction due to the skirts position behind the moving bell mouth. A circulation of cooling air will thus pass over the head, walls, and cooling fins of the piston as indicated by the arrows. On the upward stroke the relative pressures in the channels are, to a certain degree, reversed and a flow will take place in a direction opposite to that shown by the arrows.

The relative speed of passage of cooling the heated surface may be controlled, to a certain degree, by varying the diameter of the insert to be used and thus varying the relative sizes of the two channels or passageways A and B. I have found, however, that it is advisable to have the effective crosssectional area of the passage B considerably greater than that of passage A.

I claim:

1. In a cooling system for internal combustion engine pistons, in combination a piston having an elongated skirt, an insert adapted to be fixedly secured in said piston, said insert being substantially cylindrical in form and having its upper end terminating adjacent the head of said pis ton and its lower end terminating in a bellshaped portion slightly below the skirt of said piston, said bell-shaped portion having its maximum diameter substantially equal to the outer diameter of said skirt.

2. In a cooling system for internal combustion engine pistons, in combination a. piston having an elongated skirt, an insert adapted to be fixedly secured in said piston, and spaced from the walls thereof to form two concentric annular passage ways, said insert being substantially cylindrical in form and having its upper end terminating adjacent the head of said piston and its lower end terminating in a bell-shaped portion slightly below the skirt of said piston, said bell-shaped portion having its maximum diameter substantially equal to the outer diameter of said skirt.

3. In a cooling system for internal combustion engine pistons, in combination, a piston having an elongated skirt, cooling fins Within said piston, an insert adapted to be fixedly secured in said piston, said insert being substantially cylindrical in form and having its upper end terminating adjacent'the head of said piston and its lower end terminating in a bell-shaped portion slightly below the skirt of said piston, said bell-shaped portion having its maximum diameter substantially equal to the outer diameter of said skirt.

In testimony whereof I affix my signature.

JOHN' T. RAUEN. 

